U.S. patent application number 12/934021 was filed with the patent office on 2011-01-13 for liquid delivery control method and liquid delivery control system.
This patent application is currently assigned to ARKRAY, INC.. Invention is credited to Masahiro Hanafusa.
Application Number | 20110005605 12/934021 |
Document ID | / |
Family ID | 41161814 |
Filed Date | 2011-01-13 |
United States Patent
Application |
20110005605 |
Kind Code |
A1 |
Hanafusa; Masahiro |
January 13, 2011 |
LIQUID DELIVERY CONTROL METHOD AND LIQUID DELIVERY CONTROL
SYSTEM
Abstract
The present invention provides a liquid delivery control method
for delivering a liquid 8 by generating, in a microchannel 3 in
which the liquid 8 is present, a differential pressure with respect
to the liquid 8 by using a pump 6. The microchannel 3 is provided
with a pressure loss varying portion 31 in which pressure loss
changes in the direction of flow. The leading end 8a of the liquid
8 is judged to have reached the pressure loss varying portion 31 by
detecting a change in pressure between the liquid 8 and the pump 6.
With this arrangement, the location of the leading end of the
liquid 8 can be properly detected without causing the structure
that forms the microchannel 3 to become complex.
Inventors: |
Hanafusa; Masahiro; ( Kyoto,
JP) |
Correspondence
Address: |
HAMRE, SCHUMANN, MUELLER & LARSON, P.C.
P.O. BOX 2902
MINNEAPOLIS
MN
55402-0902
US
|
Assignee: |
ARKRAY, INC.
Kyoto-shi, Kyoto
JP
|
Family ID: |
41161814 |
Appl. No.: |
12/934021 |
Filed: |
March 27, 2009 |
PCT Filed: |
March 27, 2009 |
PCT NO: |
PCT/JP2009/056236 |
371 Date: |
September 22, 2010 |
Current U.S.
Class: |
137/12 ;
137/561R |
Current CPC
Class: |
B01L 2300/16 20130101;
B01L 3/502746 20130101; G01N 35/1095 20130101; Y10T 137/0379
20150401; B01L 2200/14 20130101; B01L 3/50273 20130101; B01L
2200/0642 20130101; Y10T 137/8593 20150401; B01L 2300/087 20130101;
G01N 2035/1034 20130101; B01L 2400/0415 20130101; B01L 2300/0816
20130101; B01L 2300/14 20130101 |
Class at
Publication: |
137/12 ;
137/561.R |
International
Class: |
F15D 1/00 20060101
F15D001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 9, 2008 |
JP |
2008-101094 |
Claims
1. A liquid delivery control method for delivering a liquid by
generating, in a microchannel in which the liquid is present, a
differential pressure with respect to the liquid by using a
differential pressure generation source, the method comprising:
providing, in the microchannel, a pressure loss varying portion in
which pressure loss varies in a direction of flow; and judging that
a leading end of the liquid has reached the pressure loss varying
portion by detecting a change in pressure between the liquid and
the differential pressure generation source.
2. The liquid delivery control method according to claim 1, wherein
the pressure loss varying portion is a portion where a
cross-sectional area is decreased or increased in the direction of
flow.
3. The liquid delivery control method according to claim 1, wherein
the pressure loss varying portion is defined by wall surfaces that
have a larger surface roughness or higher water repellency than
that of wall surfaces that define portions in front of and behind
the pressure loss varying portion in the direction of flow.
4. The liquid delivery control method according to claim 2, wherein
the pressure loss varying portion includes a portion at which a
dimension in a direction perpendicular to the direction of flow
discontinuously changes in the direction of flow.
5. A liquid delivery control system, comprising: a microchannel for
allowing a liquid to flow therethrough; and a differential pressure
generation source for generating, in the microchannel, a
differential pressure with respect to the liquid; the microchannel
being provided with a pressure loss varying portion in which
pressure loss varies in a direction of flow; wherein the liquid
delivery control system further comprises: a pressure measurer for
measuring pressure between the liquid and the differential pressure
generation source; and a controller that judges that a leading end
of the liquid has reached the pressure loss varying portion based
on a change in the pressure measured by the pressure measurer.
6. The liquid delivery control system according to claim 5, wherein
the pressure loss varying portion is a portion where a
cross-sectional area is decreased or increased in the direction of
flow.
7. The liquid delivery control system according to claim 5, wherein
the pressure loss varying portion is defined by wall surfaces that
have a larger surface roughness or higher water repellency than
that of wall surfaces that define portions in front of and behind
the pressure loss varying portion in the direction of flow.
8. The liquid delivery control system according to claim 6, wherein
the pressure loss varying portion includes a portion at which a
dimension in a direction perpendicular to the direction of flow
discontinuously changes in the direction of flow.
Description
TECHNICAL FIELD
[0001] The present invention relates to a liquid delivery control
method and a liquid delivery control system, which enable the
location of the leading end of a liquid delivered in a microchannel
to be precisely determined.
BACKGROUND ART
[0002] Delivery of a liquid in a microchannel is carried out in,
for example, a blood analyzer that analyzes a specific component in
blood. Blood analyzers dilute specimen blood to a prescribed
dilution factor with, for example, a diluent followed by reacting
the diluted blood with a reagent and detecting the development of
color to analyze the presence and concentration of a specific
component. In addition, blood analyzers count the numbers of blood
cells such as erythrocytes or leukocytes according to changes in
electrical resistance when diluted blood passes over a narrow
cross-section. In order to carry out these analyses, it is
necessary to deliver fixed amounts of blood, diluent as well as
diluted blood from a certain location to another location as
accurately as possible.
[0003] FIG. 15 shows an example of a conventional liquid delivery
control system (see, for example, Patent Document 1). The liquid
delivery control system shown in the figure comprises an analyzer
91 and a cartridge 92. The analyzer 91 is able to house the
cartridge 92. The cartridge 92 includes a microchannel 93 for
delivering a liquid 98 such as blood or diluent to a main body made
of a resin, for example, and a starting reservoir 94A and an ending
reservoir 94B, which are connected by the microchannel 93. A pump
96 is connected to the starting reservoir 94A via a pipe. The pump
96 is housed in the analyzer 91, and a differential pressure is
generated in front of and behind the liquid 98 by increasing
pressure on the upstream side of the liquid 98. A CPU 97 is
provided in the analyzer 91.
[0004] In the liquid delivery control system shown in the figure,
the location of the leading end of the liquid 98 is detected in the
following manner. Electrodes 95A, 95B and 95C are provided in the
cartridge 92. The electrode 95A is exposed in the starting
reservoir 94A, the electrode 95C is exposed in the ending reservoir
94B, and the electrode 95B is exposed at a suitable location in the
microchannel 93. These electrodes 95A, 95B and 95C are connected to
the CPU 97 via wires and connectors provided in the cartridge 92.
When a differential pressure is generated by the pump 96, the
liquid 98 begins to be delivered from the starting reservoir 94A
towards the ending reservoir 94B. When the liquid 98 reaches the
electrode 95B, there is electrical continuity between the
electrodes 95A and 95B. As a result, the CPU 97 judges that the
leading end of the liquid 98 has reached the location of the
electrode 95B. As liquid delivery continues, the liquid 98 reaches
the ending reservoir 94B. As a result, there is electrical
continuity between the electrodes 95A and 95C, and the CPU 97
judges that the liquid 98 has reached the ending reservoir 94B. If
liquid delivery is temporarily interrupted when the liquid 98 has
reached the electrode 95B, a fixed amount of the liquid 98 can be
retained within the microchannel 93. In addition, once the liquid
98 has been determined to have reached the ending reservoir 94B,
further unnecessary continuation of liquid delivery can be
avoided.
[0005] In addition to the method described above that uses the
presence or absence of electrical continuity between the electrodes
95A, 95B and 95C to detect the location of the liquid 98, another
method has been proposed that consists of providing reflective
films that reflect light at a plurality of locations in the
microchannel 93, and then detecting whether or not light radiated
towards the reflective films is blocked by the liquid 98.
[0006] However, the providing of the electrodes 95A, 95B and 95C
along with the wires and connectors used to connect them ends up
making the structure of the cartridge 92 complex. In addition, in
the case of using the liquid 98 as a conductor, current flows
through the liquid 98. As a result, there is the risk of the liquid
98 being electrolyzed by this current. In the case of detecting
using light, it is necessary to provide the cartridge 92 with the
above-mentioned reflective films as well as a portion for allowing
transmission of light, again making the structure of the cartridge
92 complex. In addition, it is also necessary to provide the
analyzer 91 with light-emitting devices such as LED modules as well
as light-receiving devices such as photodiodes. Moreover, it is
necessary to adjust the optical axis so that light from the LED
modules and the like is properly radiated onto the reflective
films.
[0007] Patent Document 1: JP-A-2007-71655
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0008] An object of the present invention, which is conceived under
the above-described circumstances, is to provide a liquid delivery
control method and a liquid delivery control system which are able
to properly detect the leading end of a liquid without making the
structure that forms a microchannel complex.
Means for Solving the Problems
[0009] According to a first aspect of the present invention, there
is provided a liquid delivery control method for delivering a
liquid by generating, in a microchannel in which the liquid is
present, a differential pressure with respect to the liquid by
using a differential pressure generation source. The method
comprises the steps of providing, in the microchannel, a pressure
loss varying portion in which pressure loss varies in the direction
of flow, and judging that the leading end of the liquid has reached
the pressure loss varying portion by detecting a change in pressure
between the liquid and the differential pressure generation
source.
[0010] Pressure loss as referred to in the present invention refers
to resistance to which a liquid is subjected from the walls of a
channel and the like when it flows through the channel, and a
pressure loss varying portion refers to a portion at which pressure
loss to which the liquid is subjected when flowing over a unit
length changes in the direction of flow. The object of the present
invention of detecting the location of the leading end of a liquid
is achieved by utilizing the considerable change in resistance
force attributable to surface tension that occurs when the leading
end has reached the pressure loss varying portion.
[0011] In a preferred embodiment of the present invention, the
pressure loss varying portion is a portion where the
cross-sectional area is decreased or increased in the direction of
flow.
[0012] In a preferred embodiment of the present invention, the
pressure loss varying portion is defined by wall surfaces that have
a larger surface roughness or higher water repellency than that of
the wall surfaces that define the portions in front of and behind
the pressure loss varying portion in the direction of flow.
[0013] In a preferred embodiment of the present invention, the
pressure loss varying portion includes a portion at which the
dimension in a direction perpendicular to the direction of flow
discontinuously changes in the direction of flow.
[0014] According to a second aspect of the present invention, there
is provided a liquid delivery control system comprising a
microchannel for allowing a liquid to flow therethrough, and a
differential pressure generation source for generating, in the
microchannel, a differential pressure with respect to the liquid.
The microchannel is provided with a pressure loss varying portion
in which pressure loss varies in the direction of flow. The liquid
delivery control system further comprises a pressure measurer for
measuring pressure between the liquid and the differential pressure
generation source, and a controller that judges that the leading
end of the liquid has reached the pressure loss varying portion
based on a change in the pressure measured by the pressure
measurer.
[0015] In a preferred embodiment of the present invention, the
pressure loss varying portion is a portion where the
cross-sectional area is decreased or increased in the direction of
flow.
[0016] In a preferred embodiment of the present invention, the
pressure loss varying portion is defined by wall surfaces that have
a larger surface roughness or higher water repellency than that of
the wall surfaces that define the portions in front of and behind
the pressure loss varying portion in the direction of flow.
[0017] In a preferred embodiment of the present invention, the
pressure loss varying portion includes a portion at which the
dimension in a direction perpendicular to the direction of flow
discontinuously changes in the direction of flow.
[0018] Other features and advantages of the present invention will
become clear from the following detailed description of the
invention provided with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a system block diagram showing an example of a
liquid delivery control system according to the present
invention;
[0020] FIG. 2 is an enlarged plan view showing a pressure loss
varying portion provided in the liquid delivery control system
shown in FIG. 1;
[0021] FIG. 3 is a system block diagram including a sectional view
taken along line III-III in FIG. 1;
[0022] FIG. 4 is a graph of pressure change in a liquid delivery
control method using the liquid delivery control system shown in
FIG. 1;
[0023] FIG. 5 is a system block diagram showing the state of liquid
delivery in the liquid delivery control system shown in FIG. 1;
[0024] FIG. 6 is a system block diagram showing a state in which
the liquid has reached a pressure loss varying portion in the
liquid delivery control system shown in FIG. 1;
[0025] FIG. 7 is a system block diagram showing a state in which
the liquid has been removed from a starting reservoir in the liquid
delivery control system shown in FIG. 1;
[0026] FIG. 8 is a system block diagram showing the state of liquid
delivery in the liquid delivery control system shown in FIG. 1;
[0027] FIG. 9 is a system block diagram showing a state in which
the liquid has reached an ending reservoir in the liquid delivery
control system shown in FIG. 1;
[0028] FIG. 10 is an enlarged plan view showing another example of
a pressure loss varying portion provided in the liquid delivery
control system according to the present invention;
[0029] FIG. 11 is a graph of pressure change in a liquid delivery
control method using the pressure loss varying portion shown in
FIG. 10;
[0030] FIG. 12 is an enlarged plan view showing still another
example of a pressure loss varying portion provided in the liquid
delivery control system according to the present invention;
[0031] FIG. 13 is a system block diagram showing another example of
a liquid delivery control system according to the present
invention;
[0032] FIG. 14 is a graph of pressure change in a liquid delivery
control method using the liquid delivery control system shown in
FIG. 13; and
[0033] FIG. 15 is a system block diagram showing an example of a
conventional liquid delivery control system.
BEST MODE FOR CARRYING OUT THE INVENTION
[0034] Preferred embodiments of the present invention are described
below with reference to the drawings.
[0035] FIGS. 1 to 3 show an example of a liquid delivery control
system according to the present invention. The liquid delivery
control system of the present embodiment comprises an analyzer 1
and a cartridge 2. The analyzer 1 and the cartridge 2 use the
liquid delivery control method according to the present invention
to carry out analyses using an optical method on a specific
component such as hemoglobin or C-reactive protein in blood, or to
determine blood cell counts such as erythrocyte or leukocyte
count.
[0036] The analyzer 1 is designed to allow the cartridge 2 to be
mounted therein, and includes a pressure sensor 5, a pump 6 and a
CPU 7. In addition to these constituents, the analyzer 1 further
includes light-emitting means such as an LED module and
light-receiving means such as a photodiode for carrying out
analyzes using an optical method.
[0037] The pressure sensor 5 is disposed in a pathway that connects
the pump 6 and the cartridge 2, and is for reading pressure in this
portion. A relatively small pressure sensor is used as the pressure
sensor 5, such as a semiconductor strain gauge-type pressure sensor
or piezoelectric pressure sensor. Output signals from the pressure
sensor 5 are sent to the CPU 7.
[0038] The pump 6 is a differential pressure generating source for
generating a differential pressure in front of and behind a liquid
8 in order to deliver the liquid 8 within the cartridge 2. In the
present embodiment, differential pressure is generated by applying
positive pressure to the upstream side of the liquid 8.
[0039] The CPU 7 is a controller that controls operation of the
analyzer 1. The pressure sensor 5, the pump 6, and the
above-mentioned LED module and photodiode are connected to the
controller. In order to realize a liquid delivery control method to
be described later, the CPU 7 controls operation of the pump 6 by
receiving output signals from the pressure sensor 5.
[0040] The cartridge 2 is mounted in the analyzer 1 and provides a
field where blood serving as the analysis target of the analyzer 1
is diluted to a state suitable for analysis and then analyzed. As
shown in FIG. 3, in the present embodiment, the cartridge 2 is made
up of a substrate 21 and a transparent cover 22 which are bonded
together, and is designed in the manner of a so-called disposable
type in which it is disposed of following completion of a single
analysis.
[0041] The substrate 21 is made of e.g. a resin such as an epoxy
resin, and serves as the base of the cartridge 2. The transparent
cover 22 is made of e.g. a transparent resin such as an acrylic or
silicone resin, and allows transmission of light from the LED
module. Minute surface irregularities are formed on the side of the
transparent cover 22 that is laminated to the substrate 21. Thus, a
microchannel and a plurality of reservoirs required for analysis
processing, including a microchannel 3, a starting reservoir 4A and
an ending reservoir 4B, are formed in the cartridge 2.
[0042] The starting reservoir 4A is a reservoir into which the
liquid 8, such as blood, diluent or a diluted blood consisting of a
mixture thereof, is introduced. In the case where the liquid 8 is
blood, blood sampled from a test subject is dropped into the
starting reservoir 9A with a dropper and the like. In the case
where the liquid 8 is a diluent, the starting reservoir 8 may
retain the diluent in advance or a prescribed amount of diluent may
be introduced from the analyzer 1 into the reservoir. In the case
where the liquid 8 is diluted blood, blood and diluent may be mixed
and agitated in the starting reservoir 8. The pump 6 is connected
to the starting reservoir 4A in the state in which the cartridge 2
is mounted in the analyzer 1.
[0043] The ending reservoir 4B is a reservoir into which the liquid
8 is delivered from the starting reservoir 4A. In the case where
the liquid 8 is blood or diluent, the ending reservoir 4B may be
used to mix and agitate the blood and diluent. In the case where
the liquid 8 is diluted blood, the ending reservoir 4B may serve as
a location for carrying out analysis processing on the diluted
blood, or retain the diluted blood following completion of analysis
processing. In the present embodiment, the ending reservoir 4B is
open to the atmosphere via a pathway within the analyzer 1.
[0044] The microchannel 3 connects the starting reservoir 4A and
the ending reservoir 4B, and is a pathway for delivering the liquid
8 from the starting reservoir 4A to the ending reservoir 4B. A
pressure loss varying portion 31 is formed in the microchannel 3.
The pressure loss varying portion 31 is a portion in which pressure
loss varies considerably in the direction of flow, and in the
present embodiment, is provided by partially reducing the width of
the microchannel 3 as shown in FIG. 2. More specifically, in
contrast to the width of the microchannel 3 at locations other than
the pressure loss varying portion 31 being about 200 .mu.m, the
width of the pressure loss varying portion 31 is about 80 .mu.m.
Discontinuous portions 31a, at which the width discontinuously
changes, are provided on the upstream end and downstream end of the
pressure loss varying portion 31. A constant width portion other
than the pressure loss varying portion 31 and circular arc sections
of the pressure loss varying portion 31, which are provided near
the upstream end and near the downstream end thereof, are connected
at the discontinuous portions 31a. The height of the microchannel
3, including the pressure loss varying portion 31, is constant at
about 200 .mu.m.
[0045] A liquid delivery control method that uses the analyzer 1
and the cartridge 2 is described below with reference to FIG. 1 and
FIGS. 4 to 8.
[0046] FIG. 4 shows a pressure P detected by the pressure sensor 5
in this liquid delivery control method. The pressure P is a
relative pressure based on a value of 0 for atmospheric pressure,
and is equivalent to the pressure difference in front of and behind
the liquid 8. Time t is plotted on the horizontal axis. First, as
shown in FIG. 1, the liquid 8 is introduced into the starting
reservoir 4A at time t0. At this time, the pump 6 does not operate
and a differential pressure capable of delivering the liquid 8 is
not generated.
[0047] Next, the pump 6 begins to apply positive pressure according
to a command from the CPU 7. As a result, the pressure P rises and
differential pressure is generated in front of and behind the
liquid 8. This being the case, as shown in FIG. 5, the liquid 8
begins to be delivered towards the ending reservoir 4B. This figure
shows a state in which the leading end 8a of the liquid 8 has
reached a location between the starting reservoir 4A and the
pressure loss varying portion 31 at time t1 in FIG. 4. The pressure
P at this time is a normal pressure Pn of about e.g. 1 kPa.
[0048] As the liquid continues to be delivered, as shown in FIG. 6,
the leading end 8a reaches the pressure loss varying portion 31.
When the leading end 8a comes into contact with the discontinuous
portion 31a in particular, large resistance force is generated due
to the action of surface tension. Consequently, as shown in FIG. 4,
the pressure P in the pathway between the starting reservoir 4A and
the pump 6 rises in a stepwise manner at time t2. The pressure P at
this time is a high pressure Ph of about 2 kPa. The CPU 7 judges
that the leading end 8a of the liquid 8 has reached the pressure
loss varying portion 31 when the pressure P has risen from the
normal pressure Pn to the high pressure Ph, based on an output
signal from the pressure sensor 5.
[0049] During analysis processing by the analyzer 1 and the
cartridge 2, the CPU 7 uses the arrival of the liquid 8 at the
pressure loss varying portion 31 as a trigger for beginning a
certain process. For example, if the application of positive
pressure from the pump 6 is temporarily interrupted at time t2 and
the liquid 8 remaining in the starting reservoir 4A is delivered to
another reservoir, a prescribed amount of the liquid 8 can be
retained in the microchannel 3, as shown in FIG. 7. When the
application of positive pressure from the pump 6 is then resumed,
the prescribed amount of the liquid 8 begins to move through the
microchannel 3 as shown in FIG. 8 at time t3. The prescribed amount
of the liquid 8 is then delivered to the ending reservoir 4B as
shown in FIG. 9 at time t4. In the case where the liquid 8 is
blood, a prescribed amount of blood can be retained in preparation
for agitation in the ending reservoir 4B serving as an agitation
reservoir. Alternatively, in the case where the liquid 8 is diluted
blood, a prescribed amount of the diluted blood can be introduced
into the ending reservoir 4B that serves as a location for carrying
out analysis.
[0050] The advantages of the liquid delivery control method and
liquid delivery control system of the present embodiment are
described below.
[0051] According to the present embodiment, in order to detect the
arrival of the leading end 8a of the liquid 8 at the pressure loss
varying portion 31 of the microchannel 3, it is not necessary to
provide a plurality of electrodes, wires, connectors or reflective
films in the cartridge 2 or provide light-emitting means and
light-receiving means for detecting location in the analyzer 1. In
the present embodiment, the only component that is provided
exclusively for detecting the location of the leading end 8a is the
pressure sensor 5. This pressure sensor 5 is not required to be
provided in the cartridge 2, but rather is only required to be
installed at a suitable location in the pathway that connects the
pump 6 and the cartridge 2. Thus, the arrival of the leading end 8a
of the liquid 8 at the pressure loss varying portion 31 can be
properly detected without causing the structure of the analyzer 1
and the cartridge 2 to become excessively complex.
[0052] Since the pressure loss varying portion 31 is a portion
where the cross-sectional area is partially reduced, when the
leading end 8a reaches the pressure loss varying portion 31, a
resistance force acts that inhibits delivery of the liquid 8. Thus,
if application of pressure from the pump 6 is interrupted at the
time the pressure P has increased in a stepwise manner from the
normal pressure Pn to the high pressure Ph, the leading end 8a of
the liquid 8 can be reliably retained in the pressure loss varying
portion 31. This is suitable for retaining a prescribed amount of
the liquid 8 in the microchannel 3.
[0053] Moreover, the discontinuous portion 31a provided in the
upstream end of the pressure loss varying portion 31 generates a
considerably large resistance force due to surface tension when the
leading end 8a has come into contact therewith. Due to this
resistance force, it becomes easier for the leading end 8a to, be
retained in the upstream end of the pressure loss varying portion
31. This is preferable for retaining a prescribed amount of the
liquid 8 in the microchannel 3.
[0054] FIGS. 10 to 14 show other embodiments of the present
invention. In these figures, the elements that are identical or
similar to those of the foregoing embodiment are designated by the
same reference signs as those used in the foregoing embodiment.
[0055] FIG. 10 shows another example of a pressure loss varying
portion of a liquid delivery control system according to the
present invention. The pressure loss varying portion 31 shown in
this figure has a width which is larger than that of the portions
in front of and behind it. The portions where the pressure loss
varying portion 31 and the portions in front of and behind it are
connected comprise discontinuous portions 31a.
[0056] FIG. 11 is a graph showing the pressure P in a liquid
delivery control method that uses a liquid delivery control system
provided with this type of pressure loss varying portion 31. Liquid
delivery begins at time t0, and the leading end 8a of the liquid 8
reaches the pressure loss varying portion 31 at time t2. At this
time t2, since the liquid 8 enters a portion in which the
cross-sectional area increases rapidly, the pressure P rapidly
decreases from the normal pressure Pn to a low pressure P1. When
this pressure change is detected by the pressure sensor 5, the CPU
7 judges that the leading end 8a has reached the pressure loss
varying portion 31. According to this embodiment as well, arrival
of the leading end 8a of the liquid 8 at the pressure loss varying
portion 31 can be properly detected without causing the structure
of the analyzer 1 and the cartridge 2 to become excessively
complex.
[0057] FIG. 12 shows still another example of a pressure loss
varying portion of a liquid delivery control system according to
the present invention. In the present embodiment, the pressure loss
varying portion 31 is formed by dividing the inner surface of the
microchannel 3 into a portion that is comparatively water-repellent
and a portion that is comparatively hydrophilic. The microchannel 3
has a uniform cross-sectional area. A hydrophilic treatment agent
32 is applied to the inner surface of the microchannel 3. However,
there is also an intermittent portion of the inner surface of the
microchannel 3 where this hydrophilic treatment agent 32 is not
applied. In this portion, liquid is repelled more easily than in
other portions, and this portion serves as the pressure loss
varying portion 31.
[0058] When the leading end 8a of the liquid 8 that has been
delivered through the microchannel 3 reaches the pressure loss
varying portion 31, surface tension increases rapidly. The pressure
P rises rapidly due to resistance force generated by this sudden
increase in surface tension. This pressure change is transmitted
from the pressure sensor 5 to the CPU 7, so that the CPU 7 detects
that the leading end 8a of the liquid 8 has reached the pressure
loss varying portion 31.
[0059] According to this embodiment as well, arrival of the leading
end 8a of the liquid 8 at the pressure loss varying portion 31 can
be properly detected without causing the structure of the analyzer
1 and the cartridge 2 to become excessively complex. In addition,
the pressure loss varying portion 31 can be formed without
increasing or decreasing the cross-sectional area of the
microchannel 3. Change in the pressure P can be further increased
by providing surface treatment that enhances water repellency at
the portion corresponding to the pressure loss varying portion
31.
[0060] Moreover, the pressure loss varying portion 31 may also be
provided by carrying out surface treatment on a portion of the
inner surface of the microchannel 3 so that surface roughness at
that portion becomes larger than those portions in front and behind
thereof in the direction of flow. The larger the surface roughness
of the inner surface is, the greater the resistance force applied
to the leading end 8a of the liquid 8 is. Thus, it is possible to
cause the pressure P to rise rapidly, thereby making it possible to
detect that the leading end 8a has reached the pressure loss
varying portion 31.
[0061] FIG. 13 shows another example of a liquid delivery control
system according to the present invention. The liquid delivery
control system of the present embodiment differs from the liquid
delivery control system shown in FIG. 1 in that three pressure loss
varying sections 31a, 31b and 31c are provided in the microchannel
3. These pressure loss varying portions 31a, 31b and 31c are
arranged along a straight line at intervals in the direction of
flow. The respective configurations of the pressure loss varying
portions 31a, 31b and 31c are the same as that of the pressure loss
varying portion 31 shown in FIG. 2.
[0062] FIG. 14 is a graph showing the pressure P in a liquid
delivery control method that uses the liquid delivery control
system of the present embodiment. The liquid 8 begins to be
delivered from the starting reservoir 4A at time t0 and the leading
end 8a reaches the pressure loss varying portion 31a at time t1. At
this time, the pressure P rises from a normal pressure Pn1 to the
high pressure Ph. As a result, the CPU 7 detects that the leading
end 8a has reached the pressure loss varying portion 31a. When the
leading end 8a passes the pressure loss varying portion 31a at a
time beyond time t1, the pressure P changes to a normal pressure
Pn2 in order to deliver the liquid 8. The normal pressure Pn2 is
slightly higher than the normal pressure Pn1. This is due to the
addition of pressure loss generated when the liquid 8 passes
through the pressure loss varying portion 31a having a smaller
cross-sectional area. Normal pressures Pn3 and Pn4 subsequently
also gradually become higher for the same reason.
[0063] Next, when the leading end 8a reaches the pressure loss
varying portion 31b at time t2, the pressure P again rises from the
normal pressure Pn2 to the high pressure Ph. As a result the CPU 7
detects that the leading end 8a has reached the pressure loss
varying portion 31b. The leading end 8a then reaches the pressure
loss varying portion 31c at time t3 after having been delivered at
the normal pressure Pn3 that is slightly higher than the normal
pressure Pn2. When this happens, the pressure P rises from the
normal pressure Pn3 to the high pressure Ph, and the CPU 7 detects
that the leading end 8a has reached the pressure loss varying
portion 31c. Subsequently, the leading end 8a reaches the ending
reservoir 4B at time t4 after having been delivered at the normal
pressure Pn4 that is slightly higher than the normal pressure
Pn3.
[0064] In this manner, by providing a plurality of pressure loss
varying portions 31a, 31b and 31c in the single microchannel 3, the
pressure P rises to the high pressure Ph by a number of times equal
to the number of the pressure loss varying portions 31a, 31b and
31c. Since these pressure rises do not occur simultaneously, the
pressure rises is discretely detected by the pressure sensor 5 and
the CPU 7. Thus, the leading end 8a can be sequentially detected to
have reached a plurality of locations in the direction of flow.
[0065] The liquid delivery control method and liquid delivery
control system according to the present invention are not limited
to the embodiments described above. The specific structure of the
liquid delivery control method and liquid delivery control system
according to the present invention can be varied in design in
various ways.
[0066] In the case of partially changing the cross-sectional area
as means for forming the pressure loss varying portion 31, height,
for example, may be partially varied in addition to or instead of
partially varying width. A negative pressure may be applied to the
downstream side of the liquid 8 instead of applying a positive
pressure to the upstream side of the liquid 8 in order to generate
differential pressure in front of and behind the liquid 8. The
liquid delivery control method and liquid delivery control system
according to the present invention do not necessarily need to be
designed as an analyzer and a cartridge for testing blood as
previously described, but may instead be used in an application
such as quantitatively delivering a liquid within a microchannel or
carrying out liquid delivery with even greater accuracy for the
timing of that liquid delivery.
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